High-frequency module

ABSTRACT

A high-frequency module includes a directivity switching switch unit that switches an end portion of a first sub line, which is connected to an output terminal, and first and second resistor switching switch units that switch first and second termination resistors which are connected to the first sub line. The directivity of coupled output in the first sub line of a first directional coupler is able to be switched and detection accuracy of a high-frequency signal is able to be improved by improving isolation characteristics of the first directional coupler to improve the directivity.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2015-015781 filed on Jan. 29, 2015 and is a ContinuationApplication of PCT Application No. PCT/JP2016/050456 filed on Jan. 8,2016. The entire contents of each application are hereby incorporatedherein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a high-frequency module including adirectional coupler to detect a high-frequency signal transmittedthrough a signal path.

2. Description of the Related Art

An existing high-frequency circuit 500 illustrated in FIG. 12 includes aswitch circuit 503 connecting an antenna ANT and one of a receptioncircuit 501 and a transmission circuit 502 in a switching manner, and aconnection state of the switch circuit 503 is controlled to be switchedbased on a control signal that is input to a control terminal 503 a.When the antenna ANT and the reception circuit 501 are connected, areception signal input to the antenna ANT passes through a filter 504and is input to a low noise amplifier 505. When the antenna ANT and thetransmission circuit 502 are connected, a transmission signal outputfrom a power amplifier 506 passes through an isolator 507 and is outputfrom the antenna ANT.

In the high-frequency circuit 500, a directional coupler 508 including amain line 508 a located in a signal path 502 a through which thetransmission signal passes is provided, a termination resistor R isconnected to an end portion (port), at the isolation side, of a sub line508 b that is electromagnetically coupled to the main line 508 a, and anautomatic power control (APC) circuit 509 is connected to an end portion(port) thereof at a coupling side. The gain of the power amplifier 506is adjusted based on a control signal for gain adjustment, which isoutput from the APC circuit 509 in accordance with the signal level ofthe transmission signal detected by the directional coupler 508, suchthat the signal level of the transmission signal to be output from thepower amplifier 506 is substantially constant.

In recent years, as communication apparatuses including mobilecommunication terminals, such as cellular phones and portableinformation terminals, and wireless LAN terminals, and the like, acommunication apparatus that includes a plurality of communicationsystems for making communication based on different communicationstandards, such as GSM (Global System for Mobile Communications,registered trademark) standards, W-CDMA (Wideband Code Division MultipleAccess) standards, LTE (Long Term Evolution) standards, and Bluetooth(registered trademark) standards and is compatible with communicationbased on a plurality of communication standards (multiple modes) hasbeen provided. In the communication apparatus that includes theplurality of communication systems and is therefore compatible with themultiple modes, predetermined frequency bands are assigned to therespective communication systems and communication is performed usingthe plurality of frequency bands (multiple bands). As the communicationapparatus that is compatible with the multiple modes as described above,a communication apparatus including a communication system for receivingsignals from GPS (Global Positioning System) satellite in addition tothe respective communication systems for making communication based onthe above-described communication standards has been also provided.

The communication apparatus that is compatible with the multiple modesand multiple bands uses a plurality of multiband antennas to improvequality and reliability of communication and improve communicationspeed. For example, the same reception signal is received using aplurality of multiband antennas with a diversity system. Then, theplurality of same reception signals received by the respective multibandantennas are compared and communication is performed using the multibandantenna which is the best in a reception state among the multibandantennas or the plurality of same reception signals received by theplurality of multiband antennas are combined to remove noise containedin the reception signals, thereby improving the quality and reliabilityof communication.

For example, communication is performed using a plurality of multibandantennas to which different frequency bands are respectively assignedwith a carrier aggregation system. That is to say, the plurality ofmultiband antennas are used for communication and the respectivefrequency bands are combined to be simultaneously used, therebyimproving communication volume.

In the communication apparatus including the plurality of communicationsystems and employing a communication method, such as the diversitysystem and the carrier aggregation system, the high-frequency circuit500 is required to have a function of causing the directional coupler508 to detect, with high accuracy, transmission signals of the pluralityof frequency bands, which are output from the respective communicationsystems, and high-frequency signals of the plurality of frequency bands,which are returned after the transmission signals are reflected by theantenna ANT, in order to further improve transfer characteristics of thetransmission signals of predetermined frequency bands of the respectivecommunication systems and suppress reflection and flow-in of thetransmission signals of the predetermined frequency bands to thetransmission circuit 502 side due to mismatching in the antenna ANT.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide techniques thatare capable of switching the directivity of coupled output of adirectional coupler and improving detection accuracy of a high-frequencysignal by improving isolation characteristics.

A high-frequency module according to a preferred embodiment of thepresent invention includes a first directional coupler including a firstmain line located in a first signal path of a high-frequency circuit anda first sub line which is electromagnetically coupled to the first mainline; and a switch unit that switches directivity of coupled output inthe first sub line, wherein the switch unit includes a first inputterminal which is connected to one end portion of the first sub line; asecond input terminal which is connected to the other end portion of thefirst sub line; an output terminal from which the coupled output inputto the first input terminal or the second input terminal in the firstsub line is output; a plurality of first resistor switching terminals towhich a plurality of first termination resistors with differentresistance values are connected in a one-to-one correspondence manner; aplurality of second resistor switching terminals to which a plurality ofsecond termination resistors with different resistance values areconnected in a one-to-one correspondence manner; a directivity switchingswitch unit which connects one of the first input terminal and thesecond input terminal and the output terminal in a switching manner; theplurality of first termination resistors which are connected to thefirst input terminal in parallel; the plurality of second terminationresistors which are connected to the second input terminal in parallel;a first resistor switching switch unit which connects at least one ofthe first termination resistors to the first input terminal when thedirectivity switching switch unit connects the second input terminal tothe output terminal; and a second resistor switching switch unit whichconnects at least one of the second termination resistors to the secondinput terminal when the directivity switching switch unit connects thefirst input terminal to the output terminal.

In a high-frequency module according to a preferred embodiment of thepresent invention, the first resistor switching switch unit connects atleast one of the plurality of first termination resistors to the firstinput terminal (one end portion of the sub line) when the directivityswitching switch unit connects the second input terminal (the other endportion of the first sub line) to the output terminal. When thedirectivity switching switch unit connects the first input terminal (oneend portion of the sub line) to the output terminal, the second resistorswitching switch unit connects at least one of the plurality of secondtermination resistors to the second input terminal (the other endportion of the sub line). With these, the directivity of the coupledoutput in the first sub line of the first directional coupler is able tobe switched.

In a high-frequency module according to a preferred embodiment of thepresent invention, when the coupled output in the first sub line isinput to the second input terminal from the other end portion, the firsttermination resistor with an optimum resistance value is connected tothe one end portion of the sub line with the first input terminalinterposed therebetween in accordance with a frequency band of ahigh-frequency signal as a detection target, the high-frequency circuitthat is connected to the first main line, and the fluctuation of load,and in the same or similar manner when the coupled output in the firstsub line is input to the first input terminal from the one end portion,the second termination resistor with an optimum resistance value isconnected to the other end portion of the sub line with the second inputterminal interposed therebetween. With this configuration, thedirectivity is able to be improved by eliminating mismatching caused byfluctuation in the frequency of the coupled output, and the like andimproving the isolation characteristics of the first directionalcoupler, thus improving the detection accuracy of the high-frequencysignal.

Furthermore, the switch unit may preferably further include a firstinductor which is connected between the first input terminal and theoutput terminal; and a second inductor which is connected between thesecond input terminal and the output terminal.

With this configuration, when the coupled output in the first sub lineis input to the second input terminal from the other end portion, thefirst inductor and off capacitance of the directivity switching switchunit define an LC parallel resonance circuit between the first inputterminal and the output terminal. By setting the inductance of the firstinductor such that the resonant frequency of the LC parallel resonancecircuit is a frequency at which isolation characteristics are desired tobe improved, the isolation characteristics between the first inputterminal and the output terminal at a frequency of a signal that isinput to the second input terminal is able to be improved. When thecoupled output in the first sub line is input to the first inputterminal from the one end portion, the second inductor and the offcapacitance of the directivity switching switch unit define an LCparallel resonance circuit between the second input terminal and theoutput terminal. By setting the inductance of the second inductor in thesame or similar manner as for the first inductor, the isolationcharacteristics between the second input terminal and the outputterminal at a frequency of a signal that is input to the first inputterminal are able to be improved.

The switch unit may preferably further include a capacitor which isconnected between the first input terminal and the second inputterminal.

With this configuration, a parasitic inductance component in the firstsub line and the capacitor define an LC parallel resonance circuitbetween the first input terminal and the second input terminal. Bysetting the shape of the first sub line, such as the line length and thewidth thereof, and the capacitance of the capacitor such that theresonant frequency of the LC parallel resonance circuit is a frequencyat which isolation characteristics are desired to be improved, theisolation characteristics between the first input terminal and thesecond input terminal at a desired frequency are able to be improved.

A high-frequency module according to a preferred embodiment of thepresent invention may preferably include a multilayer substrateincluding a laminate of a plurality of insulating layers and in whichthe first directional coupler and the switch unit are provided, whereinthe switch unit includes a switch IC component mounted on the multilayersubstrate, and the first termination resistors and the secondtermination resistors are provided in the switch IC component.

With this configuration, a circuit to switch the directivity of thefirst directional coupler is able to be easily formed only by mountingthe switch IC component on the multilayer substrate.

Furthermore, a high-frequency module according to a preferred embodimentof the present invention may preferably include a multilayer substrateincluding a laminate of a plurality of insulating layers and in whichthe first directional coupler and the switch unit are provided, whereinthe switch unit includes a switch IC component mounted on the multilayersubstrate, and the first termination resistors and the secondtermination resistors are respectively defined by chip componentsmounted on the multilayer substrate.

With this configuration, a circuit to switch the directivity of thefirst directional coupler is able to be provided with a practicalconfiguration by the switch IC component and the chip components. Inaddition, the resistance values are able to be easily changed only byreplacing the chip components defining the first and second terminationresistors, so as to increase the degree of freedom in design of theresistance values.

Furthermore, it is preferable that a first connection wiring connectingthe one end portion of the first sub line and the first input terminaland a second connection wiring connecting the other end portion of thefirst sub line and the second input terminal be provided on or ininsulating layers which are different from each other.

With this configuration, electromagnetic coupling between the firstconnection wiring and the second connection wiring is able to be reducedor prevented, so as to improve the isolation characteristics between thefirst input terminal and the second input terminal.

Furthermore, the first directional coupler may preferably be defined bya surface mount device mounted on the multilayer substrate.

With this configuration, the first directional coupler is able to beconnected to the high-frequency circuit only by mounting the surfacemount device on the multilayer substrate.

It is preferable that a high-frequency module according to a preferredembodiment of the present invention further includes a seconddirectional coupler including a second main line located in a secondsignal path and a second sub line which is electromagnetically coupledto the second main line, wherein the switch unit includes a third inputterminal which is connected to one end portion of the second sub line; afourth input terminal which is connected to the other end portion of thesecond sub line; a plurality of third termination resistors which areconnected to the third input terminal in parallel; and a plurality offourth termination resistors which are connected to the fourth inputterminal in parallel, the directivity switching switch unit connects anyone of the first to fourth input terminals and the output terminal in aswitching manner, the switch unit further includes a third resistorswitching switch unit which connects at least one of the thirdtermination resistors to the third input terminal when the directivityswitching switch unit connects the fourth input terminal to the outputterminal; and a fourth resistor switching switch unit which connects atleast one of the fourth termination resistors to the fourth inputterminal when the directivity switching switch unit connects the thirdinput terminal to the output terminal, and the switch unit selectivelyswitches directivity of coupled output in any one of the first sub lineand the second sub line.

This configuration is practical because the first and second directionalcouplers provided in the first and second main lines, respectively, areable to detect high-frequency signals passing through the first andsecond main lines in both directions.

According to various preferred embodiments of the present invention, adirectivity switching switch unit switches an end portion of a first subline that is connected to an output terminal and first and secondresistor switching switch units switch first and second terminationresistors that are connected to the first sub line. With thisconfiguration, directivity of coupled output in the first sub line of afirst directional coupler is able to be switched, and detection accuracyof the high-frequency signal is able to be improved by improvingisolation characteristics of the first directional coupler to improvethe directivity.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating a high-frequency moduleaccording to a first preferred embodiment of the present invention.

FIG. 2 is a diagram illustrating a high-frequency circuit included inthe high-frequency module in FIG. 1.

FIG. 3 is a circuit diagram for explaining improvement of isolationcharacteristics by adding an inductor.

FIGS. 4A and 4B are graphs illustrating bandpass characteristics of thecircuit in FIG. 3, where FIG. 4A is a graph illustrating the bandpasscharacteristics of a line at a signal output side, and FIG. 4B is agraph illustrating the bandpass characteristics of a line at anisolation side.

FIG. 5 is a circuit diagram for explaining a comparative example of FIG.3.

FIGS. 6A and 6B are graphs illustrating bandpass characteristics of thecircuit in FIG. 5, where FIG. 6A is a graph illustrating the bandpasscharacteristics of a line at a signal output side, and FIG. 6B is agraph illustrating the bandpass characteristics of a line at anisolation side.

FIG. 7 is a circuit diagram for explaining improvement of the isolationcharacteristics by adding a capacitor.

FIGS. 8A and 8B are graphs illustrating bandpass characteristics of thecircuit in FIG. 7, where FIG. 8A is a graph illustrating the bandpasscharacteristics of a line at a signal output side, and FIG. 8B is agraph illustrating the bandpass characteristics of a line at anisolation side.

FIG. 9 is a circuit diagram for explaining a comparative example of FIG.7.

FIGS. 10A and 10B are graphs illustrating bandpass characteristics ofthe circuit in FIG. 9, where FIG. 10A is a graph illustrating thebandpass characteristics of a line at a signal output side, and FIG. 10Bis a graph illustrating the bandpass characteristics of a line at anisolation side.

FIG. 11 is a view illustrating a high-frequency circuit included in ahigh-frequency module according to a second preferred embodiment of thepresent invention.

FIG. 12 is a view illustrating a high-frequency circuit included in anexisting high-frequency module.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First PreferredEmbodiment

A first preferred embodiment of the present invention will be describedwith reference to FIG. 1 to FIG. 10. FIG. 1 and FIG. 2 illustrate onlymain configurations according to preferred embodiments of the presentinvention and other configurations are not illustrated in the drawingsfor making explanation easy. FIG. 11 to be referred to later in thedescription also illustrates only main configurations as in FIG. 2 butexplanation thereof is omitted in the following description.

A high-frequency module 1 illustrated in FIG. 1 and FIG. 2 is mounted ona communication apparatus (not illustrated) which makes communicationusing a plurality of frequency bands based on a plurality ofcommunication standards and is compatible with multiple modes andmultiple bands. The communication apparatus includes a plurality ofcommunication systems to make communication based on differentcommunication standards, such as GSM standards, W-CDMA standards, LTEstandards, and Bluetooth standards, and a plurality of communicationsystems to make communication in different bands (frequency bands) basedon the same communication standards. The high-frequency module 1connects a plurality of antennas A1 and A2 provided in the communicationapparatus and the plurality of communication systems (not illustrated)mounted on the communication apparatus in a switching manner. Thehigh-frequency module 1 is located at a subsequent stage to the antennasA1 and A2 that are capable of transmitting and receiving communicationsignals of the plurality of frequency bands and compatible with themultiple bands.

The high-frequency module 1 includes first and second directionalcouplers 3 and 4, a switch IC 5, a switch IC component 6, chipcomponents 7 defining first to fourth inductors L1 to L4, chipcomponents 8 defining first and second capacitors C1 and C2, and anoutput control circuit (output control component) 9, and includes amultilayer substrate 2 including a plurality of (for example, five)insulating layers 2 a to 2 f that are laminated. The switch IC 5, theswitch IC component 6, the chip components 7 and 8, and the outputcontrol circuit (output control component) 9 are mounted on landelectrodes 22 that mount components, which are provided on a mountingsurface 21 of the multilayer substrate 2, and are electrically connectedto a plurality of outer connection terminals 24 provided on a backsurface 23 of the multilayer substrate 2 with wiring electrodes 10provided in the multilayer substrate 2 interposed therebetween.

The multilayer substrate 2 is preferably defined by a common multilayersubstrate, such as a low-temperature co-fired ceramics (LTCC) multilayersubstrate and a resin multilayer substrate made of glass epoxy resin,for example. The chip components 7 and 8 that adjust characteristics ofthe switch IC 5 and the switch IC component 6 and provide a matchingcircuit, and various filter circuits, are mounted on the multilayersubstrate 2 as necessary. Electrodes, such as the land electrodes 22,the outer connection terminals 24, and the wiring electrodes 10 arepreferably provided on and in the multilayer substrate 2 using aconductive material containing Cu, Ag, or other suitable material.

The wiring electrodes 10 include in-plane conductors and via conductorsprovided in the five insulating layers 2 a to 2 f as necessary, and theswitch IC 5, the switch IC component 6, and the respective chipcomponents 7 and 8 provided on the multilayer substrate 2 areelectrically connected to one another with the wiring electrodes 10 todefine first and second signal paths SL1 and SL2, first to fourthconnection wirings 10 a to 10 d, and other circuit elements.Furthermore, the first and second directional couplers 3 and 4, andcircuit elements, such as capacitors and inductors defining the matchingcircuit, and various filter circuits are appropriately defined by thewiring electrodes 10. It should be noted that the directional coupler 4is not illustrated in FIG. 1.

The directional coupler 3 includes a first main line 31 and a first subline 32. The first main line 31 is located in the first signal path SL1connecting an antenna terminal ANT1 a (outer connection terminal 24) towhich the antenna A1 is connected and a first common terminal ANT1 ofthe switch IC 5. The first sub line 32 is electromagnetically coupled tothe first main line 31. The first connection wiring 10 a connects oneend portion 32 a of the first sub line 32 and a first input terminal 6 aof the switch IC 6 and the second connection wiring 10 b connects theother end portion 32 b of the first sub line 32 and a second inputterminal 6 b of the switch IC 6. As illustrated in FIG. 1, the first andsecond connection wirings 10 a and 10 b are respectively provided on thedifferent insulating layers 2 d and 2 f of the multilayer substrate 2.

The directional coupler 4 includes a second main line 41 and a secondsub line 42. The second main line 41 is located in the second signalpath SL2 connecting an antenna terminal ANT2 a (outer connectionterminal 24) to which the antenna A2 is connected and a second commonterminal ANT2 of the switch IC 5. The second sub line 42 iselectromagnetically coupled to the second main line 41. The thirdconnection wiring 10 c connects one end portion 42 a of the second subline 42 and a third input terminal 6 c of the switch IC 6 and the fourthconnection wiring 10 d connects the other end portion 42 b of the secondsub line 42 and the fourth input terminal 6 d of the switch IC 6.Although not illustrated in the drawings, in the same or similar manneras the first and second connection wirings 10 a and 10 b, the third andfourth connection wirings 10 c and 10 d are respectively provided on thedifferent insulating layers of the multilayer substrate 2.

As illustrated in FIG. 2, the switch IC 5 includes the first and secondcommon terminals ANT1 and ANT2 and a plurality of switching terminals51. The first and second common terminals ANT1 and ANT2 are connected tothe antenna terminals ANT1 a and ANT2 a provided in the multilayersubstrate 2 with the first and second signal paths SL1 and SL2,respectively. The individual antennas A1 and A2 are connected to thecommon terminals ANT1 and ANT2, respectively, by connecting theindividual antennas A1 and A2 to the antenna terminals ANT1 a and ANT2a, respectively. Corresponding communication systems (not illustrated)are respectively connected to the switching terminals 51, and any one ofthe common terminals ANT1 and ANT2 and any one of the switchingterminals 51 are connected to each other in a switching manner to selectthe antenna A1 or A2 that is used by each of the communication systems.The configuration of the switch IC 5 is well known and the specificconfiguration thereof is therefore omitted.

The switch IC 6 (corresponding to a “switch unit”) switches thedirectivity of coupled output in each of the first sub line 32 of thedirectional coupler 3 and the second sub line 42 of the directionalcoupler 4, and includes the first to fourth input terminals 6 a to 6 d,the output terminal 6 e, a directivity switching switch unit 62connecting any one of the first to fourth input terminals 6 a to 6 d andthe output terminal 6 e in a switching manner, and first to fourthresistor switching switch units 63 a to 63 d.

Each of the first to fourth resistor switching switch units 63 a to 63 dincludes a plurality of switches and a plurality of terminationresistors with different resistance values are connected to therespective switches in a one-to-one correspondence manner. For example,the first resistor switching switch unit 63 a includes first to thirdswitch elements 64 a 1 to 64 a 3. First end portions of the switchelements 64 a 1 to 64 a 3 are connected to the first input terminal 6 aand the second end portions thereof are respectively connected to oneends of a plurality of first termination resistors R11 to R13 withdifferent resistance values. The second to fourth resistor switchingswitch units 63 b to 63 d also have the same or similar configurationsas that of the first resistor switching switch unit and explanation ofthe detailed configurations thereof is omitted by applying equivalentreference numerals. It should be noted that the second ends of the firstto fourth termination resistors are connected to ground connectionelectrodes of the multilayer substrate 2 with ground terminals 6 f ofthe switch IC 6 interposed therebetween.

The directivity switching switch unit 62 includes switches 62 a to 62 dprovided so as to correspond one to one to the first to fourth inputterminals 6 a to 6 d. First ends of the switches 62 a to 6 d arerespectively connected to the first to fourth input terminals to whichthey correspond and the second ends thereof are connected to the outputterminal 6 e. In the present preferred embodiment, the directivityswitching switch unit 62 and the first to fourth resistor switchingswitch units 63 a to 63 d are defined by, if necessary, respectivelyconnecting inductors, capacitors, and resistors to electric field effecttransistors (FETs).

When the directivity switching switch unit 62 connects the second inputterminal 6 b to the output terminal 6 e, the first resistor switchingswitch unit 63 a connects any one of the first termination resistors R11to R13 to the first input terminal 6 a. When the directivity switchingswitch unit 62 connects the first input terminal 6 a to the outputterminal 6 e, the second resistor switching switch unit 63 b connectsany one of the second termination resistors R21 to R23 to the secondinput terminal 6 b. In this case, the coupled output in the first subline 32 is output from the output terminal 6 e.

When the directivity switching switch unit 62 connects the fourth inputterminal 6 d to the output terminal 6 e, the third resistor switchingswitch unit 63 c connects any one of the third termination resistors R31to R33 to the third input terminal 6 c. When the directivity switchingswitch unit 62 connects the third input terminal 6 c to the outputterminal 6 e, the fourth resistor switching switch unit 63 d connectsany one of the fourth termination resistors R41 to R43 to the fourthinput terminal 6 d. In this case, the coupled output in the second subline 42 is output from the output terminal 6 e.

As described above, switching of the connection state in the directivityswitching switch unit 62 and the first to fourth resistor switchingswitch units 63 a to 63 d causes the switch IC component 6 toselectively switch the directivity of the coupled output in either ofthe first sub line 32 or the second sub line 42.

As illustrated in FIG. 2, the first inductor L1 (for example, about 100nH) is connected between the first input terminal 6 a and the outputterminal 6 e, the second inductor L2 (for example, about 100 nH) isconnected between the second input terminal 6 b and the output terminal6 e, the third inductor L3 (for example, about 100 nH) is connectedbetween the third input terminal 6 c and the output terminal 6 e, andthe fourth inductor L4 (for example, about 100 nH) is connected betweenthe fourth input terminal 6 d and the output terminal 6 e. Furthermore,the first to fourth inductors L1 to L4 are preferably respectivelydefined by the chip components 7 mounted on the multilayer substrate 2.Accordingly, the inductances of the first to fourth inductors L1 to L4are able to be easily adjusted only by replacing the chip components 7,so as to change adjustment ranges of the inductances of the first tofourth inductors L1 to L4. In the same or similar manner as the first tofourth termination resistors, at least any one of the first to fourthinductors L1 to L4 may be provided in the switch IC 6.

Furthermore, as illustrated in FIG. 2, the first capacitor C1(corresponding to a “capacitor” of, for example, about 0.3 pF) isconnected between the first input terminal 6 a and the second inputterminal 6 b and the second capacitor C2 (for example, about 0.3 pF) isconnected between the third input terminal 6 c and the fourth inputterminal 6 d. The first and second capacitors C1 and C2 are preferablyrespectively defined by the chip components mounted on the multilayersubstrate 2. Accordingly, the capacitances of the first and secondcapacitors C1 and C2 are able to be easily adjusted only by replacingthe chip components 8, so as to increase adjustment ranges of thecapacitances of the first and second capacitors C1 and C2. In the sameor similar manner as the first to fourth termination resistors R1 to R4,at least any one of the first and second capacitors C1 and C2 may beprovided in the switch IC component 6.

As illustrated in FIG. 2, the output control circuit 9 is connected tothe output terminal 6 e of the switch IC 6. For example, a portion of asignal passing through the main line is able to be taken out from thesub line with less influence on the signal passing through the main lineby, for example, setting an electromagnetic coupling quantity betweenthe main line and the sub line in each of the first and seconddirectional couplers 3 and 4 to approximately 20 dB. The signal takenout from the sub line is output from the output terminal 6 e and acontrol signal for gain adjustment is output to a power amplifier orother suitable component connected to the switching terminals 51 of theswitch IC 5 from the output control circuit 9 based on the outputsignal.

How the isolation characteristics between a path connecting the firstinput terminal 6 a and the output terminal 6 e of the switch IC 6 and apath connecting the second input terminal 6 b and the output terminal 6e are improved by adding the first inductor L1 will be described withreference to FIG. 3 to FIG. 6B. The transverse axis in each of FIGS. 4Aand 4B and FIGS. 6A and 6B indicates frequency (GHz) and thelongitudinal axis therein indicates passage loss (dB). In each of FIGS.4A and 4B and FIGS. 6A and 6B, the output terminal 6 e corresponds to afirst port, the input terminal 6 a corresponds to a second port, and theinput terminal 6 b corresponds to a third port. Although the case inwhich the input terminal 6 b is connected to the first sub line 32 ofthe first directional coupler 3 is described as an example, the same orsimilar effects as those which will be described below are also providedin the case in which any one of the input terminals 6 a, 6 c, and 6 d isconnected to the first sub line 32 or the second sub line 42 anddescription thereof is therefore omitted.

When the input terminal 6 b is connected to the sub line 32 of thedirectional coupler 3 with a signal path indicated by a bold solid linein FIG. 3, the bandpass characteristics (insertion loss) in a lineconnected to the sub line 32 indicate the characteristics that are asillustrated in FIG. 4A and are substantially the same or similar to thebandpass characteristics (insertion loss) in a path connected to the subline 32 as illustrated in FIG. 6A when the first and second inductors L1and L2 are not provided as illustrated in FIG. 5. As described above,the second inductor L2 produces less adverse influence on the insertionloss in the signal path connected to the sub line 32. It should be notedthat in the present preferred embodiment, the center frequency in thefrequency band of the communication signal passing through the main line32 is preferably about 2.17 GHz, for example.

On the other hand, the bandpass characteristics in a path that is notconnected to the sub line 32 as indicated by a bold dashed line in FIG.3 indicate the characteristics as illustrated in FIG. 4B because the offcapacitance Cf of the switch 62 a (directivity switching switch unit 62)and the first inductor L1 illustrated in FIG. 3 define an LC parallelresonance circuit. In the present preferred embodiment, the centerfrequency in the frequency band of the signal passing through the mainline 31 is preferably about 2.17 GHz, for example. Therefore, a value ofthe inductor L1 is selected such that the resonant frequency of the LCparallel resonance circuit is preferably about 2.17 GHz, for example. Incomparison with the bandpass characteristics of approximately −34 dB(about 2.17 GHz) in a line that is not connected to the sub line 32 asillustrated in FIG. 6B when the first and second inductors L1 and L2 arenot provided as illustrated in FIG. 5, the bandpass characteristics inthe path that is not connected to the sub line 32 in FIG. 3 are improvedto approximately −56 dB, for example. As described above, the additionof the first and second inductors L1 and L2 reduces or prevents leakageof the signal to the path that is not connected to the sub line 32without deteriorating the insertion loss in the path that is connectedto the sub line 32 in the frequency band of the signal passing throughthe main line 31, so as to improve the isolation characteristics betweenthe first input terminal 6 a and the second input terminal 6 b.

How the isolation characteristics between the first input terminal 6 aand the second input terminal 6 b of the switch IC 6 are improved byadding the first capacitor C1 will be described with reference to FIG. 7to FIG. 10B. The transverse axis in each of FIGS. 8A and 8B and FIGS.10A and 10B indicates frequency (GHz) and the longitudinal axis thereinindicates passage loss (dB). In each of FIGS. 8A and 8B and FIGS. 10Aand 10B, the output terminal 6 e corresponds to the first port, theinput terminal 6 b corresponds to the second port, and the inputterminal 6 a corresponds to the third port. Although the case in whichthe input terminal 6 a is connected to the sub line 32 of thedirectional coupler 3 is described as an example, the same or similareffects as those which will be described below are also provided in thecase in which any one of the input terminals 6 b to 6 d is connected tothe first sub line 32 or the second sub line 42 and description thereofis therefore omitted.

When the input terminal 6 a is connected to the sub line of thedirectional coupler 3 as illustrated in FIG. 7, the bandpasscharacteristics (insertion loss) in a path connected to the sub line 32as indicated by a bold solid line in FIG. 7 indicate the characteristicsthat are as illustrated in FIG. 8A and are substantially the same orsimilar to the bandpass characteristics (insertion loss) in a path atthe coupling side as illustrated in FIG. 10A when the first capacitor C1is not provided as illustrated in FIG. 9. As described above, the firstcapacitor C1 produces less adverse influence on the insertion loss inthe path connected to the sub line 32.

On the other hand, the bandpass characteristics (isolationcharacteristics) in a path that is not connected to the sub line 32 asindicated by a bold dashed line in FIG. 7 indicate the characteristicsas illustrated in FIG. 8B because a parasitic inductance component Lf ofthe sub line 32 and the first capacitor C1 illustrated in FIG. 7 definean LC parallel resonance circuit. In comparison with the isolationcharacteristics of approximately −40 dB in a path that is not connectedto the sub line 32 as illustrated in FIG. 10B when the first capacitorC1 is not provided as illustrated in FIG. 9, the isolationcharacteristics in the line at the isolation side in FIG. 7 are improvedto approximately −43 dB, for example. As described above, the additionof the first capacitor C1 improves the isolation characteristics withoutdeteriorating the insertion loss in the path that is connected to thesub line 32.

As described above, the directivity of the coupled output in the firstsub line 32 of the first directional coupler 3 provided in the firstsignal path SL1 or the second sub line 42 of the second directionalcoupler 4 provided in the second signal path SL2 is able to be switched,so as to detect a high-frequency signal passing through each of thefirst and second signal paths SL1 and SL2 in both directions.

When the coupled output in the first sub line 32 is input to the secondinput terminal 6 b from the other end portion 32 b, any one of the firsttermination resistors R11 to R13 with an optimum resistance value isconnected to the one end portion 32 a of the sub line 32 with the firstinput terminal 6 a interposed therebetween in accordance with thefrequency band of the high-frequency signal as a detection target, thehigh-frequency circuit that are connected to the first signal path SL1,and the fluctuation of the load. When the coupled output in the firstsub line 32 is input to the first input terminal 6 a from the one endportion 32 a, any one of the second termination resistors R21 to R23with an optimum resistance value is connected to the other end portion32 b of the sub line 32 with the second input terminal 6 b interposedtherebetween. With this configuration, mismatching in the impedancebetween the end portion of the sub line and the directivity switchingswitch unit 62 is improved and the isolation characteristics of thefirst directional coupler 3 are improved, so as to improve thedirectivity. The detection accuracy of the high-frequency signal in thefirst directional coupler 3 is therefore improved.

In the same or similar manner, the third termination resistors R3connected to the third input terminal 6 c (the end portion 42 a of thesecond sub line 42) or the fourth termination resistors R4 connected tothe fourth input terminal 6 d (the other end portion 42 b of the secondsub line 42) are switched. With this configuration, mismatching in theimpedance between the end portion of the second sub line 42 and thedirectivity switching switch unit 62 is improved and the directivity ofthe second directional coupler 4 is improved, so as to improve theisolation characteristics. The detection accuracy of the high-frequencysignal in the second directional coupler 4 is therefore improved.

Moreover, when the coupled output in the first sub line 32 is input tothe second input terminal 6 b from the other end portion 32 b, the firstinductor L1 and the off capacitance Cf of the switch 62 a define the LCparallel resonance circuit between the first input terminal 6 a and theoutput terminal 6 e. By setting the inductance of the first inductor L1such that the resonant frequency of the LC parallel resonance circuit isa frequency at which the isolation characteristics are desired to beimproved, a signal input from the second input terminal 6 b is able tobe prevented from coming around to the first input terminal 6 a side.When the coupled output in the first sub line 32 is input to the firstinput terminal 6 a from the one end portion 32 a, the second inductor L2and the off capacitance Cf of the switch 62 b define the LC parallelresonance circuit between the second input terminal 6 b and the outputterminal 6 e. Therefore, by setting the inductance of the secondinductor L2 in the same or similar manner as for the first inductor L1,a signal input from the first input terminal 6 a is prevented fromcoming around to the second input terminal 6 b side. As described above,the isolation characteristics between the first input terminal 6 a andthe second input terminal 6 b are able to be improved by arranging theinductor L1 in parallel with the path connecting the first inputterminal 6 a and the output terminal 6 e and arranging the inductor L2in parallel with the path connecting the second input terminal 6 b andthe output terminal 6 e.

Furthermore, by setting the inductances of the third inductor L3 andfourth inductor L4 in the same or similar manner as for the first andsecond inductors L1 and L2, the isolation characteristics between thethird input terminal 6 c and the fourth input terminal 6 d are able tobe improved.

The parasitic inductance component in the first sub line 32 and thefirst capacitor C1 connected to the first sub line 32 in parallel definethe LC parallel resonance circuit between the first input terminal 6 aand the second input terminal 6 b. By setting the shape of the first subline 32, such as the line length and the width thereof, and thecapacitance of the first capacitor C1 such that the resonant frequencyof the LC parallel resonance circuit is a frequency at which theisolation characteristics are desired to be improved, the isolationcharacteristics between the first input terminal 6 a and the secondinput terminal 6 b at a desired frequency are able to be improved.Moreover, in the same or similar manner, by setting the shape of thesecond sub line 42, such as the line length and the width thereof, andthe capacitance of the second capacitor C2, the isolationcharacteristics between the third input terminal 6 c and the fourthinput terminal 6 d at a desired frequency are able to be improved.

When the plurality of first to fourth termination resistors are providedin the switch IC 6, a circuit that switches the directivities of thefirst and second directional couplers 3 and 4 is easily provided only bymounting the switch IC 6 on the multilayer substrate 2. In addition, thehigh-frequency module 1 is able to be reduced in size and thecharacteristics of the first and second directional couplers 3 and 4 areable to be made stable.

Furthermore, the first connection wiring 10 a and the second connectionwiring 10 b are respectively provided on the different insulating layers2 d and 2 f. Therefore, electromagnetic coupling between the firstconnection wiring 10 a and the second connection wiring 10 b is reducedor prevented, so as to improve the isolation characteristics between thefirst input terminal 6 a and the second input terminal 6 b. In the sameor similar manner, the third connection wiring 10 c and the fourthconnection wiring 10 d are respectively provided on the differentinsulating layers. Therefore, electromagnetic coupling between the thirdconnection wiring 10 c and the fourth connection wiring 10 d is reducedor prevented, so as to improve the isolation characteristics between thethird input terminal 6 c and the fourth input terminal 6 d.

Second Preferred Embodiment

A second preferred embodiment of the present invention will be describedwith reference to FIG. 11. The high-frequency module 1 in the secondpreferred embodiment is different from the above-described firstpreferred embodiment in that the first to fourth termination resistorsare preferably defined by chip components 11 mounted on the multilayersubstrate 2 as illustrated in FIG. 11. Moreover, the first directionalcoupler 3 is preferably defined by a surface mount device 12 mounted onthe multilayer substrate 2 and the second directional coupler 4 ispreferably defined by a surface mount device 13 mounted on themultilayer substrate 2. Other configurations and operations are the sameor similar as those in the above-described first preferred embodimentand explanation of the configurations and operations thereof are omittedby applying the same reference numerals.

With this configuration, the resistance values of the first to fourthtermination resistors are able to be easily changed only by replacingthe chip components 11, so as to increase the change ranges of theresistance values. Furthermore, the first and second directionalcouplers 3 and 4 are mounted on the main surface of the multilayersubstrate 2. Therefore, the isolation characteristics between thedirectional couplers and wirings and other circuit elements incorporatedin the multilayer substrate are able to be improved in comparison withthe configuration in which the first and second directional couplers 3and 4 are incorporated in the multilayer substrate.

It should be noted that the present invention is not limited to theabove-described preferred embodiments. In addition to theabove-described preferred embodiments, various changes may be madewithout departing from the gist thereof and the above-describedconfigurations may be combined in any manner. For example, the numbersof circuit elements, such as the first to fourth termination resistorsand the directional couplers 3 and 4 are not limited to theabove-described numbers and it is sufficient that the necessary numbersof circuit elements are provided in accordance with the number ofcommunication systems and the number of antennas A1 and A2 included inthe communication apparatus. Although each of the first to fourthtermination resistors is preferably defined by the circuit includingthree resistors in the preferred embodiments, each of the resistorswitching switch units 63 a to 63 d may select one of the threeresistors or equal to or more than two resistors at the same time. Thisconfiguration is able to increase the selection ranges of thetermination resistors.

The first and second directional couplers 3 and 4 and the switch IC 6may preferably be integrally defined by a surface mount device. Forexample, providing the first and second directional couplers 3 and 4 onthe semiconductor substrate of the switch IC 6 reduces the areasoccupied by the directional couplers and the switch IC and reduces thehigh-frequency module in size.

Although in the above-described preferred embodiments, the directivityswitching switch unit 62 and the first to fourth resistor switchingswitch units 63 a to 63 d are preferably primarily defined by theelectric field effect transistors, they may include various switchingelements, such as a PIN diode, a bipolar transistor, and anelectrostatic induction-type transistor, for example.

The antennas that are connected to the switch IC 5 are not limited tothe above-described antennas A1 and A2 for multiple bands and aplurality of antennas for single bands corresponding to the respectivebands that are used in the used communication systems may preferably beconnected to the switch IC 5. It is sufficient that the numbers ofantennas and communication systems which are connected to the switch ICare appropriately set to optimum numbers in accordance with theconfiguration of the communication apparatus on which the high-frequencymodule 1 is mounted.

Preferred embodiments of the present invention can be widely applied tohigh-frequency modules including a high-frequency circuit in which adirectional coupler that detects a high-frequency signal transmittedthrough a signal path is provided.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A high-frequency module comprising: a firstdirectional coupler including a first main line located in a firstsignal path and a first sub line which is electromagnetically coupled tothe first main line; and a switch unit that switches directivity ofcoupled output in the first sub line; wherein the switch unit includes:a first input terminal which is connected to one end portion of thefirst sub line; a second input terminal which is connected to anotherend portion of the first sub line; an output terminal from which thecoupled output that is input to the first input terminal or the secondinput terminal in the first sub line is output; a directivity switchingswitch unit which connects one of the first input terminal and thesecond input terminal and the output terminal in a switching manner; aplurality of first termination resistors which are connected to thefirst input terminal in parallel; a plurality of second terminationresistors which are connected to the second input terminal in parallel;a first resistor switching switch unit which connects at least one ofthe first termination resistors to the first input terminal when thedirectivity switching switch unit connects the second input terminal tothe output terminal; and a second resistor switching switch unit whichconnects at least one of the second termination resistors to the secondinput terminal when the directivity switching switch unit connects thefirst input terminal to the output terminal.
 2. The high-frequencymodule according to claim 1, wherein the switch unit further includes: afirst inductor which is connected between the first input terminal andthe output terminal; and a second inductor which is connected betweenthe second input terminal and the output terminal.
 3. The high-frequencymodule according to claim 1, wherein the switch unit further includes acapacitor which is connected between the first input terminal and thesecond input terminal.
 4. The high-frequency module according to claim1, further comprising: a multilayer substrate that includes a pluralityof insulating layers that are laminated and in which the firstdirectional coupler and the switch unit are provided; wherein the switchunit includes a switch IC mounted on the multilayer substrate; and thefirst termination resistors and the second termination resistors areprovided in the switch IC.
 5. The high-frequency module according toclaim 1, further comprising: a multilayer substrate that includes aplurality of insulating layers that are laminated and in which the firstdirectional coupler and the switch unit are provided; wherein the switchunit includes a switch IC mounted on the multilayer substrate; and thefirst termination resistors and the second termination resistors includechip components mounted on the multilayer substrate.
 6. Thehigh-frequency module according to claim 4, wherein a first connectionwiring connecting the one end portion of the first sub line and thefirst input terminal and a second connection wiring connecting theanother end portion of the first sub line and the second input terminalare provided in the insulating layers which are different from eachother.
 7. The high-frequency module according to claim 4, wherein thefirst directional coupler includes a surface mount device mounted on themultilayer substrate.
 8. The high-frequency module according to claim 1,further comprising: a second directional coupler including a second mainline located in a second signal path and a second sub line which iselectromagnetically coupled to the second main line; wherein the switchunit further includes: a third input terminal which is connected to oneend portion of the second sub line; a fourth input terminal which isconnected to another end portion of the second sub line; a plurality ofthird termination resistors which are connected to the third inputterminal in parallel; and a plurality of fourth termination resistorswhich are connected to the fourth input terminal in parallel; whereinthe directivity switching switch unit connects any one of the first tofourth input terminals and the output terminal in a switching manner; athird resistor switching switch unit which connects at least one of thethird termination resistors to the third input terminal when thedirectivity switching switch unit connects the fourth input terminal tothe output terminal; and a fourth resistor switching switch unit whichconnects at least one of the fourth termination resistors to the fourthinput terminal when the directivity switching switch unit connects thethird input terminal to the output terminal; and the switch unitselectively switches directivity of coupled output in any one of thefirst sub line and the second sub line.
 9. The high-frequency moduleaccording to claim 4, wherein the multilayer substrate is a resinmultilayer substrate made of glass epoxy resin.
 10. The high-frequencymodule according to claim 5, wherein the multilayer substrate is a resinmultilayer substrate made of glass epoxy resin.
 11. The high-frequencymodule according to claim 4, wherein the multilayer substrate is made ofa low-temperature co-fired ceramics.
 12. The high-frequency moduleaccording to claim 5, wherein the multilayer substrate is made of alow-temperature co-fired ceramics.
 13. The high-frequency moduleaccording to claim 1, wherein the first signal path connects an antennaterminal to which an antenna is connected and a first common terminal ofthe switch unit.
 14. The high-frequency module according to claim 8,wherein the second signal path connects an antenna terminal to which anantenna is connected and a first common terminal of the switch unit.